Manufacturing apparatus and method for making silicon nanowires on carbon based powders for use in batteries
Manufacturing apparatus, systems and method of making silicon (Si) nanowires on carbon based powders, such as graphite, that may be used as anodes in lithium ion batteries are provided. In some embodiments, an inventive tumbler reactor and chemical vapor deposition (CVD) system and method for growing silicon nanowires on carbon based powders in scaled up quantities to provide production scale anodes for the battery industry are described.
1. A manufacturing apparatus for growing silicon nanowires on carbon based powders, comprising:
an elongated CVD chamber;
an elongated metal process tube positioned within the CVD chamber;
one or more tumbler reactors removably positioned within the elongated metal process tube and configured to rotate within the elongated metal process tube, said one or more tumbler reactors configured to receive the carbon based powder, said one or more tumbler reactors each comprising an elongated cylindrical metal tube and each having a gas distribution manifold positioned therein and extending the substantial length of the tumbler reactor;
one or more scrapers configured to scrape at least a portion of the inner walls of the one or more tumbler reactors;
wherein the elongated metal process tube and the one or more tumbler reactors positioned within the elongated metal process tube are configured to be heated according to a process recipe,
wherein the elongated metal process tube comprises a vacuum port for injecting purge gases and an exhaust port connected to a vacuum pump to provide a low pressure environment,
wherein the gas distribution manifold comprises a U-shaped gas injection member comprising a plurality of injection ports positioned along the gas injection members for injecting a mixture of process gases uniformly into the tumbler reactor, the one or more scrapers being attached to the gas injection member, and
wherein the one or more tumbler reactors each comprise an end plate at both ends of the tumbler reactor.
2. The manufacturing apparatus of claim 1 wherein the injection ports are substantially equally distributed along the gas injection member to provide substantially uniform distribution of the mixture of process gases within the one or more tumbler reactors.
3. The manufacturing apparatus of claim 1 , wherein the one or more scrapers is positioned at one or more of the ends of the one or more tumbler reactors to scrape the powder from the periphery of the one or more tumbler reactors.
4. The manufacturing apparatus of claim 1 wherein the one or more scrapers comprises an elongated blade that extends at least a portion of the length of the one or more tumbler reactors.
5. The manufacturing apparatus of claim 1 wherein a brush member is positioned along at least a portion of the outer side of the elongated blade.
6. The manufacturing apparatus of claim 1 , wherein the one or more scrapers is integrated with the gas distribution manifold in the one or more tumbler reactors.
7. The manufacturing apparatus of claim 1 wherein the one or more tumbler reactors further comprises one or more fins mounted on one or more inner walls of the one or more tumbler reactors.
8. The manufacturing apparatus of claim 7 , wherein the one or more fins are configured to provide control of movement of the carbon-based powder in the one or more tumbler reactors.
9. The manufacturing apparatus of claim 7 wherein the one or more fins are configured to prevent the carbon based powders from slipping along or clinging to the one or more inner walls during rotation of the one or more tumbler reactors.
10. The manufacturing apparatus of claim 7 , wherein the one or more fins are configured to distribute the carbon-based powder in the one or more tumbler reactors.
11. The manufacturing apparatus of claim 1 , further comprising a carriage rail with wheels configured to support the one or more tumbler reactors and to move the one or more tumbler reactors in and out of the elongated metal process tube.
12. The manufacturing apparatus of claim 1 , further comprising a carriage rail with wheels configured to move the CVD chamber away from the elongated metal process tube and the one or more tumbler reactors.
13. The manufacturing apparatus of claim 1 , wherein the carbon based powders comprise one or more selected from the group consisting of natural graphite, artificial graphite, soft carbon, hard carbon, amorphous carbon and combinations thereof.
14. The manufacturing apparatus of claim 1 , wherein the elongated metal process tube further comprises a sequence of three active zones comprising a heating zone, a reaction zone and a cooling zone, wherein the three active zones are separated from each other by two buffer zones to allow the transition of each of the one or more tumbler reactors from an active zone to the next under controlled conditions of pressure and temperature.
15. The manufacturing apparatus of claim 1 , wherein temperature in the one or more tumbler reactors, gases concentration in the one or more tumbler reactors, and rotation of the one or more tumbler reactors are controlled by computer with automatic software for the production.
16. The manufacturing apparatus of claim 1 , wherein at least one of the end plates comprises a toothed outer edge extending the entire periphery of the end plate, said edge engaging with a rotation gear coupled with a motor to rotate the tumbler reactor.
17. The manufacturing apparatus of claim 1 , wherein the gas injection member is stationary.
18. The manufacturing apparatus of claim 1 , wherein the one or more tumbler reactors each further comprise a mesh end cap, each mesh end cap having a plurality of apertures sized such that the apertures contain the carbon-based powder within the tumbler reactor and allow the process gases to flow between the tumbler reactor and the metal process tube.